Development of a curable composition obtained by reacting a polyoxypropylene polymer having an alkenyl group and a compound having a hydrosilyl group in the presence of a platinum catalyst for use in various applications including re-peeling has been considered in view of the properties such as rapid curing ability, good curing depth, and the properties based on the structure such as affinity for various substrates, hydrophilicity, chemical stability and the like. As a method for obtaining such curable composition, a curable composition has been proposed which is obtained by reacting a polyoxypropylene polymer having an alkenyl group with organohydrogen polysiloxane having a silicon bonded hydrogen in one molecule in the presence of a platinum catalyst (e.g., JP-A-60-55056). As a method for improving compatibility and mechanical property of this curable composition, moreover, a method using, as a compound having a hydrosilyl group, organohydrogen polysiloxane having a phenyl group on the side chain has been proposed (e.g., JP-A-7-300555). In addition, a pressure-sensitive adhesive composition comprising a polyoxypropylene polymer having an alkenyl group, a compound having a hydrosilyl group, and a hydrosilylation catalyst comprising a tackifier resin has been proposed (e.g., JP-A-4-145188). However, produces resulting from curing these compositions do not necessarily have good property as an adhesive.
As other pressure-sensitive adhesives using a polyoxyalkylene polymer, pressure-sensitive adhesives using urethane crosslinking are known (e.g., JP-A-7-310066), and they have been reported to have superior properties such as adhesion to the skin, moisture permeability, water absorbability and the like. Due to urethane crosslinking, however, they are associated with problems including difficult control of curing speed, remaining unreacted isocyanate feared to have toxicity and the like.